Start with QUIT as a graceful restart

According to http://unicorn.bogomips.org/SIGNALS.html Unicorn does a graceful shutdown on QUIT and a fast shutdown on TERM, so let's try them in that order.
Merge pull request #14 from markpundsack/patch-1

Start with QUIT as a graceful restart
Make max QUIT, max TERM, and sleep interval configurable.